US20090229812A1 - Plug bypass valves and heat exchangers - Google Patents

Abstract

A bypass valve for a heat exchanger including a plurality of parallel tubular members comprises a housing having a hollow plug portion adjacent to an actuator portion. The actuator comprises a reciprocating plunger extending into the plug portion and a solenoid having a central actuator shaft attached to the plunger, wherein the actuator shaft extends upon energization of the solenoid so that the plunger prevents bypass flow through the valve. The valve also comprises a temperature sensor for sensing a temperature of the fluid flowing through the heat exchanger, the temperature sensor being electrically coupled to the solenoid through one or more conductors, wherein the temperature sensor is located at the first end of the actuator shaft and the conductors extend through the hollow interior of the actuator shaft to the second end thereof.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This is a continuation-in-part of U.S. patent application Ser. No. 11/264,494, filed Nov. 1, 2005, now pending; which is a continuation of U.S. patent application Ser. No. 09/918,082, filed Jul. 30, 2001, now abandoned; both of which are incorporated herein by reference in their entireties.
FIELD OF THE INVENTION
• This invention relates to heat exchangers, and in particular, to bypass valves for bypassing or short-circuiting flow from the heat exchanger inlet to the heat exchanger outlet under conditions where the heat transfer function of the heat exchanger is not required or is only intermittently required.
BACKGROUND OF THE INVENTION
• In certain applications, such as in the automotive industry, heat exchangers are used to cool or heat certain fluids, such as engine oil or transmission fluid or oil. In the case of transmission fluid, for instance, a heat exchanger is usually used to cool the transmission fluid. The heat exchanger is usually located remote from the transmission and receives hot transmission fluid from the transmission through supply tubing, cools it, and delivers it back to the transmission again through return tubing. However, when the transmission is cold, such as at start-up conditions, the transmission oil is very viscous and does not flow easily through the heat exchanger, if at all. In such cases, the transmission can be starved of fluid and this may cause damage to the transmission or at least erratic performance. Damage can also be caused to the transmission if the quantity of fluid returned is adequate, but is over-cooled by the heat exchanger due to low ambient temperatures. In this case, water may accumulate in the transmission fluid as a result of condensation (which normally would be vaporized at higher temperatures) and this may cause corrosion damage or transmission fluid degradation.
• In order to overcome the cold flow starvation problem, it has been proposed to insert a bypass valve between the supply and return tubing to and from the heat exchanger. This bypass valve may be temperature responsive so that it opens causing bypass flow when the transmission fluid is cold, and it closes to prevent bypass flow when the transmission fluid heats up to operating temperature. An example of such a bypass valve is shown in U.S. Pat. No. 6,253,837 issued to Thomas F. Seiler et al. While this approach works satisfactorily, the heat exchanger and bypass valve assembly becomes quite large and includes fluid inlet and outlet tubing that may not otherwise be required.
SUMMARY OF THE INVENTION
• In the present invention, the bypass valve can be incorporated as an integral part of the heat exchanger as a plug-in item that can be located anywhere desired between the inlet and outlet flow manifolds of the heat exchanger.
• According to one aspect of the invention, there is provided a bypass valve for a heat exchanger including a plurality of parallel, tubular members having adjacent wall portions defining flow openings in communication to form flow manifolds. The bypass valve comprises a housing having a hollow plug portion with opposed plug walls defining inlet and outlet openings therein, the plug walls being adapted to be sealingly mounted between selected adjacent tubular member wall portions to allow fluid flow respectively between the flow manifolds and the inlet and outlet openings. The housing also has an actuator portion located adjacent to the plug portion. Also, an actuator is releasably mounted in the actuator portion and has a reciprocating plunger extending into the plug portion to block and unblock flow between the inlet and outlet openings.
• According to another aspect of the invention, there is provided a heat exchanger comprising a plurality of parallel, tubular members having adjacent wall portions defining flow openings in communication to form inlet and outlet manifolds for the flow of fluid through the tubular members. A bypass valve includes a housing having a hollow plug portion with opposed plug walls defining inlet and outlet openings therein, the plug walls being sealingly mounted between selected adjacent tubular member wall portions to allow fluid flow respectively between the flow manifolds and the inlet and outlet openings. The housing also has an actuator portion located adjacent to the plug portion. Also, an actuator is releasably mounted in the actuator portion and has a reciprocating plunger extending into the plug portion to block and unblock flow between the inlet and outlet openings.
• According to yet another aspect of the invention, there is provided a bypass valve for a heat exchanger including a plurality of parallel tubular members having adjacent wall portions defining flow openings in communication to form flow manifolds. The bypass valve comprises a housing having a hollow plug portion with opposed plug walls defining inlet and outlet openings therein. The plug walls are adapted to be sealingly mounted between selected adjacent tubular member wall portions to allow fluid flow respectively between said flow manifolds and said inlet and outlet openings. The housing also has an actuator portion located adjacent to the plug portion. An actuator is releasably mounted in the actuator portion and comprises a reciprocating plunger extending into the plug portion and a solenoid having a central actuator shaft attached to the plunger. The actuator shaft extends upon energization of the solenoid, so that the plunger blocks flow between the inlet and outlet openings. The actuator shaft has a first end to which the plunger is attached, a second end, and a hollow interior, and the actuator further comprises bias means for urging the actuator shaft to retract upon de-energization of the solenoid so as to unblock flow between said inlet and outlet openings. A temperature sensor is provided for sensing a temperature of the fluid flowing through the heat exchanger. The temperature sensor is electrically coupled to the solenoid through one or more conductors, wherein the temperature sensor is located at the first end of the actuator shaft and the one or more conductors extend through the hollow interior of the actuator shaft to the second end thereof.
• According to yet another aspect of the invention, there is provided a heat exchanger comprising a plurality of parallel, tubular members having adjacent wall portions defining flow openings in communication to form inlet and outlet manifolds for the flow of fluid through the tubular members, wherein the heat exchanger includes a bypass valve according to the invention.
• According to yet another aspect of the invention, there is provided a bypass valve for a heat exchanger. The bypass valve comprises a housing and a temperature-responsive actuator mounted in the housing. The housing comprises a first opening and a second opening to permit fluid to flow through the valve; a first valve chamber which is arranged between the first and second openings and is in flow communication with both the first and second openings; a second valve chamber in flow communication with the first valve chamber; a third opening in communication with the second valve chamber; and a valve port which is arranged between the first and second valve chambers, wherein the second valve chamber is arranged between the third opening and the valve port. The temperature-responsive actuator comprises a reciprocating sealing member extending into the first valve chamber; a solenoid having a central actuator shaft attached to the sealing member, wherein the actuator shaft extends upon energization of the solenoid, so that the sealing member seals the valve port and blocks flow between the first and second valve chambers, wherein the actuator shaft has a first end to which the sealing member is attached, a second end, and a hollow interior; bias means for urging the actuator shaft to retract upon de-energization of the solenoid so as to unblock flow between said inlet and outlet openings; and a temperature sensor for sensing a temperature of the fluid flowing through the valve, the temperature sensor being electrically coupled to the solenoid through one or more conductors, wherein the temperature sensor is located at the first end of the actuator shaft and the one or more conductors extend through the hollow interior of the actuator shaft to the second end thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
• Preferred embodiments of the invention will now be described by way of example, with reference to the accompanying drawings, in which:
• FIG. 1 is an elevational view of a heat exchanger having a preferred embodiment of a bypass valve according to the present invention mounted therein;
• FIG. 2 is an enlarged view of the portion ofFIG. 1 indicated bycircle2;
• FIG. 3 is a perspective view, partly broken away of the bypass valve ofFIG. 2 shown in the closed position;
• FIG. 4 is a perspective view similar toFIG. 3 but showing the bypass valve in the open position;
• FIG. 5 is an elevational view similar toFIG. 2, but showing another preferred embodiment of a bypass valve according to the present invention, the valve being shown partially in cross-section;
• FIG. 6 is an elevational view similar toFIG. 2, showing yet another preferred embodiment of a bypass valve according to the present invention, the valve being shown in cross-section and in the closed position;
• FIG. 7 is an elevational view similar toFIG. 6, but showing the bypass valve ofFIG. 6 in the open position;
• FIG. 8 is a schematic view of a heat exchanger having multiple passes and more than one bypass valve;
• FIG. 9 is an elevational view of a portion of another preferred embodiment of a heat exchanger and bypass valve according to the present invention;
• FIG. 10 is an elevational view similar toFIG. 2, partly in cross section, showing yet another preferred embodiment of a bypass valve according to the present invention, with the valve being in the open position;
• FIG. 11 is an elevational view similar toFIG. 10, but showing the bypass valve ofFIG. 10 in the closed position;
• FIG. 12 is a schematic view of a heat exchange circuit including a heat exchanger and a four-port bypass valve according to the present invention;
• FIG. 13 is a schematic view of a heat exchange circuit including a heat exchanger and a three-port bypass valve according to the present invention;
• FIG. 14 is a cross-section along line14-14 ofFIG. 12 showing the four-port bypass valve in the open position;
• FIG. 15 is a cross-sectional view similar toFIG. 14, but showing the four-port bypass valve ofFIG. 14 in the closed position;
• FIG. 16 is a cross-section along line16-16 ofFIG. 13 showing the three-port bypass valve in the open position;
• FIG. 17 is a cross-sectional view similar toFIG. 16, but showing the three-port bypass valve ofFIG. 14 in the closed position; and
• FIG. 18 is a cross-sectional view of a four-port bypass valve according to another embodiment of the present invention.
DETAILED DESCRIPTION
• Referring first toFIGS. 1 and 2, a heat exchanger is generally indicated byreference numeral10, and a preferred embodiment of a bypass valve according to the present invention is generally indicated byreference numeral12.Heat exchanger10 is formed of a plurality of parallel, spaced-apart,tubular members14 preferably with enlargeddistal end portions16 that haveadjacent wall portions17 defining flow openings (not shown) in communication.Tubular members14 are preferably formed of mating plate pairs with transversely protruding cupped end portions to form theseenlarged end portions16 that also together formflow manifolds19 and21. However,tubular members14 could be formed of tubes with separate joinedenlarged end portions16, if desired. Alternatively, tubular members of uniform width or thickness could be used, in which case tubular spacers could be used between the tube ends in place of enlargeddistal end portions16. If it is not necessary to spacetubular members14 apart transversely, then such spacers would not be required. Yet another possibility would be to use transversely orientatedtubular manifolds19 and21 attached in communication with the ends oftubular members14. For the purpose of this disclosure, the term “distal end portions” is intended to include all of the above-mentioned tube member communicating wall structures.Corrugated cooling fins18 are located between thetubular members14 where thetubular members14 are spaced apart transversely.
• In the heat exchangers shown inFIGS. 1 and 2, thetubular members14 are formed into two upper and lower groups separated by central back-to-backdimpled plates20 having offsetend portions22,24. As seen best inFIG. 2, the space between offsetend portions22,24 provides a location wherebypass valve12 can be plugged intoheat exchanger10.Bypass valve12 includes ahollow plug portion26 located in this space, and which will be described in further detail below.
• As mentioned above, the enlargeddistal end portions16 have transverse openings therethrough (not shown), so that thedistal end portions16 located abovebypass valve12 are all in communication and form either an inlet or anoutlet manifold19 depending on the direction in which fluid is to flow throughheat exchanger10. Similarly, the enlargeddistal end portions16 located belowbypass valve12 are all in communication and form a respective outlet orinlet manifold21. As seen best inFIG. 1, an inlet or outlet fitting28 communicates with the enlarged distal end portions below it and an inlet or outlet fitting30 communicates with the enlarged distal end portions above it. So, for example, fluid entering inlet fitting28 travels from right to left as shown inFIG. 1 through all of thetubular members14 located abovedimpled plates20, to a similar left hand manifold formed by enlargeddistal end portions32, and then downwardly through a cross-over fitting34 into a left hand manifold in the lower section ofheat exchanger10 formed by enlargeddistal end portions32, and then back to the right end and out through outlet fitting30.Heat exchanger10 is thus called a two-pass heat exchanger and can have any number oftubular members14 above or below thedimpled plates20. In fact, there could just be onetubular member14 above or belowdimpled plates20, as illustrated in the embodiment shown inFIG. 9 and as described further below.
• Heat exchanger10 also has upper and lowerdimpled plates36. Suitable mountingbrackets40 are attached todimpled plates36 as are the inlet andoutlet fittings28,30.
• Referring next toFIGS. 3 and 4,bypass valve12 includes ahousing42 having ahollow plug portion26 with spaced-apart, opposed, flat, parallelplug side walls43 defining transversely located inlet andoutlet openings44,46 formed therein for the flow of fluid throughplug portion26 whenvalve12 is in the open position as shown inFIG. 4.Plug walls43 are sealingly mounted between selected adjacent tubularmember wall portions17 of the enlargeddistal end portions16 oftubular members14. Thedistal end portions16 have flat mating surfaces. The offsetend portions22 mate flush against their adjacent distal end portion flat surfaces and the flathousing side walls43 mate flush against the flat offsetend portions22. However, housing side or plugwalls43 would mate flush against the flat portions ofdistal end portions16, ifdimpled plates22 were not used inheat exchanger10. This mounting allows bypass fluid flow directly between selecteddistal end portions16, or respectively between the flow manifolds19 and21 and the inlet andoutlet openings44 and46, or between the inlet andoutlet fittings28,30 whenbypass valve12 is open. Bypass valve side or plugwalls43 are spaced apart a predetermined distance so as to determine the spacing between adjacent heat exchanger tubular members, especially ifdimpled plates20 are not used.
• Bypass valve housing42 also has anactuator portion48 located adjacent to and communicating withplug portion26. A temperatureresponsive actuator50 is located inhousing42.Actuator50 has acentral shaft52 attached to aremovable closure54 located remote fromplug portion26.Removable closure54 has an O-ring seal56 and is held in position by asplit pin58 passing throughopenings60 inhousing actuator portion40 and a throughhole62 inclosure54.
• Temperatureresponsive actuator50 has areciprocating barrel portion64 which forms a plunger slidably located inhousing plug portion26 to block and unblock flow between inlet andoutlet openings44,46. Aspring66 is located inhousing actuator portion48 and bears against anannular shoulder68 onbarrel64 to act as bias means to urge theactuator50 to retract so that barrel orplunger64 unblocks the flow of fluid through inlet andoutlet openings44,46 ofbypass valve12, when the actuator is not extended due to temperature, as described next below.
• Temperatureresponsive actuator50 is sometimes referred to as a thermal motor and it is a piston and cylinder type device. Barrel orplunger64 is filled with a thermal sensitive material, such as wax, that expands and contracts, causing the actuator to extend axially upon being heated to a predetermined temperature and to retract upon being cooled below this predetermined temperature. Wherebypass valve12 is used in conjunction with an automotive transmission fluid or oil cooler, this predetermined temperature is about 80 degrees Celsius, which is the temperature of the fluid from the transmission when bypass flow is no longer required.
• Referring next toFIG. 5, another preferred embodiment of a bypass valve according to the present invention is generally indicated byreference numeral70.Bypass valve70 is similar to bypassvalve12 except that a slidingplate72 bears againstcentral shaft52 and aspring74 is located inhousing actuator portion48 to urgecentral shaft52 toward thehousing plug portion26.Spring74 absorbs any pressure spikes or peaks that may occur in the inlet and outlet manifolds ofheat exchanger10. Anotch76 is formed inbarrel64 to allow the fluid to act against the end ofbarrel64 and provide this pressure relief even whenbypass valve70 is closed. A bleed hole through plunger orbarrel64 communicating with inlet opening44 could also be used in place ofnotch76 for this purpose. Otherwise,bypass valve70 is substantially the same asbypass valve12.
• Referring next toFIGS. 6 and 7, another preferred embodiment of a bypass valve according to the present invention is generally indicated byreference numeral80. Inbypass valve80, the temperatureresponsive actuator50 includes a solenoid having asolenoid coil82 and acentral actuator shaft84 attached to aplunger86.Plunger86 also has a notch or bleedhole76 to provide pressure spike relief whenvalve80 is closed.Actuator shaft84 extends upon energization ofsolenoid coil82, so thatplunger86 blocks flow between the housing inlet andoutlet openings44,46. Aspring88 located inhousing plug portion26 bears againstplunger86 to act as bias means for urging theactuator shaft84 to retract whensolenoid coil82 is de-energized.
• Atemperature sensor90 is attached toplunger86 and is in the form of a thermistor electrically coupled tosolenoid coil82 for actuation of the solenoid coil when the temperature of the fluid going throughheat exchanger10 reaches a predetermined temperature.Temperature sensor90 could be located elsewhere inbypass valve80, or even elsewhere inheat exchanger10. Preferably,temperature sensor90 is electrically connected to anelectrical control unit92 mounted inhousing actuator portion48.Electrical control unit92 is in turn electrically connected to solenoidcoil82 for controlling the movement ofplunger86 in accordance with the temperature sensed bytemperature sensor90. In this way, the opening ofbypass valve80 could be controlled to provide variable opening, rather than a simple on or off, but the latter is also possible.
• Referring next toFIG. 8, aheat exchanger100 is shown schematically and it is like twoheat exchangers10 ofFIG. 1 mounted in series. Twobypass valves102,104 are used to provide thermal modulation of the fluid flowing through theheat exchanger100.Bypass valve102 may have a predetermined temperature set point or activation temperature, andbypass valve104 may have a somewhat higher temperature set point or activation temperature.Heat exchanger100 is a four pass heat exchanger having four groups or stacks106,108,110 and112 of tubular members.
• Where bothbypass valves102 and104 are open, such as during cold flow operation, there is full fluid bypass from inlet fitting28 to outlet fitting30. Wherebypass valve102 is closed andvalve104 is open, such as during warm up or an interim temperature of fluid flowing throughheat exchanger100, there would be fluid flow through the top twopasses106 and108 ofheat exchanger100, but passes110 and112 would be bypassed throughbypass valve104. Where the fluid reaches its hot operating temperature, bothbypass valves102 and104 would close giving flow through all fourpasses106,108,110 and112 and no bypass flow at all. Additional multiples of passes and bypass valves could be used in a single heat exchanger as well. Any of the types of bypass valves described above could be used inheat exchanger100.
• Referring next toFIG. 9, other preferred embodiments of aheat exchanger113 and abypass valve115 are shown. Inbypass valve115, inlet andoutlet openings44,46 are formed in opposed plug walls114,116 and this shows that inlet andoutlet openings44,46 can be located anywhere inplug portion26 as long as one of these openings is blocked whenvalve115 is closed. Otherwise,bypass valve115 is substantially similar to or can incorporate the features of thebypass valves12,70 and80 described above. In the embodiment ofFIG. 9, plate36 (which preferably is dimpled but may be flat) and a bottom plate118 (which may also be dimpled or flat), together form atubular member120 which is one of the tubular members that make upheat exchanger113.Tubular member120 is actually a bypass channel and hasflow openings122 that communicate with the flow openings in the adjacent enlargeddistal end portions16 of adjacenttubular member14, and as such forms part of the inlet and outlet manifolds ofheat exchanger113. Instead oftubular member120, a regulartubular member14 could be used inheat exchanger113, if desired. This would produce a full flood or single pass heat exchanger.Tubular members14 may or may not have turbulizers in them or be made of dimpled plates, but thebottom tubular member120 likely would not be turbulized or have other types of flow augmentation, such as dimples.
• In the assembly ofheat exchangers10,100 and113, the various components, such as thetubular members14 or120 andfins18 are stacked together along withdimpled plates20, if desired, and upper and lowerdimpled plates36. Mounting plates orbrackets40 and inlet andoutlet fittings28,30 can be preassembled to upper and lowerdimpled plates36 or assembled along with all of the other components. Thehousing42 of thepreferred bypass valve12,70,80 or115 (without any other bypass valve components) is then placed in the desired location in the heat exchanger and the entire assembly is brazed together in a brazing furnace. It will be appreciated that in the preferred embodiments, aluminum or a brazing-clad aluminum is used for most of the parts of the heat exchangers, so that all of the parts can be brazed together in a brazing furnace. After this assembly is cooled, the desired actuator components of the bypass valves are inserted intohousing42 and theremovable closures54 are secured in position withsplit pins58.
• Having described preferred embodiments of the invention, it will be appreciated that various modifications can be made to the structures described above. For example, instead of using a thermal motor or solenoid type actuator for the bypass valves, other devices could be used as well, such as a bimetallic helix to move the barrel or plunger of the valve. The tubular members can also have other shapes or configurations as well.
• From the above, it will be appreciated that the bypass valves of the present invention are in the form of plugs that can be plugged in at any desired location in the heat exchanger with a simple rearrangement of the location of some components. The bypass valve housings actually act as a form of baffle plate to intermittently block flow between manifold portions of the heat exchangers. In fact, the bypass valves could be plugged in anywhere in the heat exchangers where it is desired to have bypass flow between the plate pairs or tubes. The bypass valve housings are brazed in place along with all of the other heat exchanger components. The actual valve elements in the actuators are then removably or releasably located in the bypass valve housings to complete the assembly. No external tubing or peripheral components are required to make the actuator valves active.
• FIGS. 10 and 11 illustrate aplug bypass valve150 according to another embodiment of the invention.Valve150 shares a number of common characteristics with theplug bypass valve80 shown inFIGS. 6 and 7, and like components thereof are identified by like reference numerals.Bypass valve150 includes a temperatureresponsive actuator50 including a solenoid having asolenoid coil82 and acentral actuator shaft84 attached toplunger86. When thesolenoid82 is energized, theactuator shaft84 is extended so as to move theplunger86 into blocking relation with the housing inlet andoutlet openings44,46 as shown inFIG. 11. When thesolenoid82 is de-energized,spring88 urges theactuator shaft84 to retract, thereby causing theplunger86 to move out of blocking relation withopenings44,46, thereby opening the valve as shown inFIG. 10.
• Temperature sensor90, preferably in the form of a thermistor, is attached toplunger86 and/or theactuator shaft84 for actuation of thesolenoid coil82 when the temperature of the fluid going throughheat exchanger10 reaches a predetermined temperature. Preferably, thetemperature sensor90 is electrically connected to anelectrical control unit92 mounted inhousing actuator portion48. More preferably, thesensor90 is connected to theelectrical control unit92 by a pair of electrical conductors or leads152,154 which extend betweensensor90 andcontrol unit92 through thehollow interior156 ofactuator shaft84.
• In the embodiment shown inFIGS. 10 and 11, theelectrical control unit92 includes acircuit board158 and is mounted to asolenoid plunger plate160 having a central aperture in which one end ofactuator shaft84 is received. The sensor leads152,154 are connected to thecircuit board158 ofcontrol unit92, as are the power supply leads162,164. The power supply leads162,164 extend through thehousing42 to a power supply (not shown). In the embodiment shown in the drawings, the power supply leads162,164 extend through theremovable closure54 ofhousing42, although this is not necessarily the case. The power supply leads162,164 may instead extend through the side wall ofactuator portion48 ofhousing42, or inbetween theactuator portion48 and theremovable closure54. Theelectrical control unit92 permits the opening ofvalve150 to be controlled in order to provide variable opening, although simple on or off opening is also possible.
• In operation, thetemperature sensor90 continuously monitors the temperature of the fluid flowing throughheat exchanger10. When thevalve150 is open as inFIG. 10, there is bypass flow through thevalve150, with thetemperature sensor90 communicating with the fluid as it flows through thevalve150 from inlet opening44 tooutlet opening46. This is the low temperature configuration ofvalve150, i.e. where the temperature of the fluid is below a predetermined temperature.
• Once the fluid inheat exchanger10 reaches the predetermined temperature, the increased temperature is sensed by thetemperature sensor90 and is communicated to theelectrical control unit92 through leads152. Theelectrical control unit92 in turn causes thesolenoid coil82 to become energized with power supplied through power supply leads162,164. When the solenoid is energized, thehollow actuator shaft84 is extended to the closed position shown inFIG. 11 so thatplunger86 blocks flow between the housing inlet andoutlet openings44,46, thereby preventing bypass flow and causing the fluid to flow through thetubular members14 ofheat exchanger10. This is the high temperature configuration ofvalve150, and in this configuration thetemperature sensor90 communicates with the fluid inheat exchanger10 through notch or bleedhole76.
• When the temperature signal communicated to thecontrol unit92 indicates that the temperature of the fluid inheat exchanger10 has dropped below the predetermined temperature, theelectrical control unit92 causes thesolenoid coil82 to become de-energized, and theplunger86 andactuator shaft84 are then pushed byspring88 back to the open position shown inFIG. 10, in which theplunger86 no longer blocks flow between the inlet andoutlet openings44,46 so as to permit bypass flow.
• The above description describes simple on/off operation ofvalve150. It will however be appreciated that the operation ofvalve150 could instead be controlled to provide variable opening. For example, once the temperature of the fluid reaches a first predetermined temperature, the actuator shaft could be partially extended so that theplunger86 moves from the fully open position as shown inFIG. 10 to a position at which it partially blocks the inlet andoutlet openings44,46 (inbetween the positions shown inFIGS. 10 and 11), thereby reducing but not stopping the bypass flow through theheat exchanger10. Once the temperature reaches a second predetermined temperature, higher than the first predetermined temperature, theplunger86 is fully extended to the closed position shown inFIG. 11, and the inlet andoutlet openings44,46 are completely blocked.
• FIG. 12 illustrates aheat exchange circuit170 including aheat exchanger172 and a preferred four-port bypass valve174 according to the invention. Any type of heat exchanger can be used with this embodiment of the present invention. A typical two pass heat exchanger is shown inFIG. 12 and has afirst manifold176, which could be an inlet or an outlet manifold, areturn manifold178 and asecond manifold180. A plurality of spaced-apartheat exchange tubes182,184 are connected between the manifolds such that, wherefirst manifold176 is an inlet manifold, fluid flows from theinlet manifold176 throughtubes182 intoreturn manifold178 where it reverses direction and comes back throughtubes184 to thesecond manifold180, which is now an outlet manifold. The flow direction can be reversed so thatsecond manifold180 is the inlet manifold and thefirst manifold176 is the outlet manifold. It will also be appreciated thatheat exchanger172 could be modified to become a single pass heat exchanger withmanifolds176,180 located at respective ends of the heat exchanger.
• Wherefirst manifold176 is an inlet manifold, it is formed with aninlet opening186 and aninlet conduit188 is connected to communicate with theinlet opening186. In this arrangement, thesecond manifold20 is the outlet manifold, and is formed with anoutlet opening190, and anoutlet conduit192 is connected to communicate with theoutlet opening190. It will be appreciated, however, that if the flow direction is reversed, theoutlet conduit192 becomes the inlet conduit andinlet conduit188 becomes the outlet conduit.Conduits188,192 are connected to inlet and outlet ports of thebypass valve174, as will be described further below. Similarly,supply conduits194,196 are also connected to ports inbypass valve174, as will be described below.Supply conduits194,196 haveend fittings198,200 for attachment to flow lines (not shown). Where theheat exchanger172 is used as a transmission oil cooler, theend fittings198,200 can be hose barbs for attaching rubber hoses between the transmission andheat exchange circuit170. However, any type ofend fittings198,200 can be used to suit the type of conduits running to and from theheat exchange circuit170.Bypass valve174 is referred to as a four port bypass valve because fourconduits188,192,194 and196 are connected to thebypass valve174.
• FIG. 13 is similar toFIG. 12 and similar reference numerals have been used inFIG. 13 and subsequent figures to indicate components that correspond to those of the embodiment shown inFIG. 12. However, theheat exchange circuit202 ofFIG. 13 has a three-port bypass valve204 which has asingle conduit205 through which it communicates withconduits188 and196, the purpose of which will be discussed below.
• FIGS. 14 and 15 provide additional detail regarding the structure of the fourport bypass valve174. Fourport valve174 has avalve housing206 defining avalve chamber208 therein. Thehousing206 has three main ports oropenings210,212 and214.Main ports210 and212 are connected toconduits192 and194 (FIG. 12).Main port214, also referred to as a valve port, communicates with twolower branch ports216,218 to whichconduits188 and196 (FIG. 12) are connected, respectively.
• Thevalve port214 has aperipherial valve seat220 facingchamber208, and amovable valve member222 for opening and closing thevalve port214.
• Thevalve member222 is in the form of an annular ring which is slidably mounted proximate to a first end of ahollow valve shaft224. In the orientation of fourport valve174 shown inFIGS. 14 and 15, the first end of thevalve shaft224 is its lower end. Movement ofvalve member222 toward the first end of thevalve shaft224 is limited by a retainingring226 received on thevalve shaft224 proximate to its first end.
• Thevalve214 further comprises avalve cover228 which is sealed to thehousing206, for example by agasket230. Thevalve cover228 has a centralapertured boss232 through which the second (upper) end of thevalve shaft224 extends. Spaced from thevalve member222 toward the second end ofvalve shaft224 are provided anannular washer234 slidably received on thevalve shaft224 and a retainingring236 attached to theshaft224 to limit movement of thewasher234 toward the second end of theshaft224. Acoil override spring238 surrounds thevalve shaft224 and bears against thewasher234 and thevalve member222 to urge them into engagement with retainingrings236,226, respectively. A seal is formed between thevalve cover228 and thevalve shaft224 by an O-ring240 which is provided in anannular groove242 surrounding the central aperture of thevalve cover228.
• Areturn spring244 is received in abore246 extending between thevalve chamber208 and thebranch ports216,218, thereby providing communication betweenbranch ports216,218 andvalve chamber208 through thevalve port214. Thebore246 extends into thebottom wall248 of thehousing206, forming acircular depression250 therein. As shown in the drawings, the first end of thevalve shaft224 extends partway into thebore246. Thecoil return spring244 extends between thedepression250 in thebottom wall248 and thevalve member222 and urges the valve member out of engagement with thevalve seat220, i.e. toward the open position shown inFIG. 14.
• Atemperature sensor252 is provided at the second end of thevalve shaft224 for sensing the temperature of fluid flowing through thebranch ports216,218 and thebore246. Thetemperature sensor252 may preferably be a thermistor. Temperature information from thesensor252 is communicated via a pair of sensor leads254,256 which extend through the hollow interior of thevalve shaft224 between its first and second ends. The sensor leads254,256 convey temperature information from thesensor252 to anelectrical control unit258 which is housed in acontrol unit compartment260. Thecompartment260 is housed inside acap262 which is secured tovalve cover228 by any suitable means, such asset screws264 as illustrated inFIG. 14. Thecontrol unit258 may preferably be attached to aplunger plate266 which is attached to the second end of thevalve shaft224, and which has an upper surface on which thecontrol unit258 is provided. Thecontrol unit258 may preferably include acircuit board268 to which the temperature sensor leads254,256 and power supply leads270,272 are connected throughappropriate connectors274,276.
• Thecontrol unit258 controls the operation of asolenoid278 having acentral bore280 through which thevalve shaft224 extends. Thesolenoid278 may preferably be provided withstuds282,284 through which it is secured to thevalve cover228. Thesolenoid278 may preferably have anannular depression290 in its upper surface into which aboss288 of theplunger plate266 extends. When thesolenoid278 becomes energized by thecontrol unit258, thevalve shaft224 is caused to move downwardly relative to the solenoid. Engagement of theplunger plate266 and thesolenoid278 provides a stop which limits the downward movement of theshaft224.
• Although not required, acoil spring286 may be provided in thecontrol unit compartment260. In the embodiment shown inFIGS. 14 and 15, one end of the coil spring engages the plunger plate while the other end engages aninternal boss292 in thecap262.
• The operation ofbypass valve174 will now be described with reference toFIGS. 12,14 and15.Heat exchange circuit170 can be operated with eitherconduit194 or196 being the inlet conduit, the other one being the outlet conduit. Whereconduit194 is the inlet conduit and receives transmission oil from the transmission (not shown), this is referred to as “normal flow”. In this case,conduit196 is the outlet conduit and returns the transmission oil to the transmission. Where, on the other hand, theconduit196 is the inlet conduit receiving the transmission oil from the transmission andconduit194 is the outlet or return conduit for delivering the oil back to the transmission, this configuration referred to as “reverse flow”.
• Dealing first with the normal flow configuration, where the temperature of the oil is lower than a predetermined temperature, such as at engine start-up conditions, the oil may be too viscous to flow throughheat exchanger172 and it is therefore necessary to bypass theheat exchanger172. Under these conditions, thevalve174 is in the open configuration with thesolenoid278 de-energized as shown inFIG. 14. The hot transmission oil flowing through theinlet conduit194 enters thevalve174 throughport212, and enters thevalve chamber208. The oil then flows through theopen valve port214, passing through a gap between thevalve element222 and thevalve seat220, into thebore246 and then exits thevalve174 through thebranch port218. As the oil flows throughbore246 it comes into contact withtemperature sensor252.
• Once thesensor252 detects that the oil temperature has reached the predetermined temperature, and conveys this information to thecontrol unit258, thecontrol unit258 energizes thesolenoid278 which causes thevalve shaft224 to extend downwardly until thevalve element222 is brought into sealed engagement with thevalve seat220. In this configuration, shown inFIG. 15, thevalve port214 is closed and bypass flow is prevented. Thus, when the oil reaches the desired operating temperature, full flow is occurring throughheat exchanger172 and bypass flow has been discontinued.
• With thevalve174 in the closed configuration shown inFIG. 15, the hot transmission oil flowing throughinlet conduit194 enters thevalve174 throughport212, flows throughvalve chamber208 and exits thevalve174 throughvalve port210. The hot oil then flows through theconduit192 and into theinlet manifold180 ofheat exchanger172. The hot oil is cooled as it passes throughheat exchanger172 and exits theheat exchanger172 throughoutlet conduit188, which is connected to theoutlet manifold186. The cooled oil flows then enters thevalve174 throughbranch port216, passes throughbore246 and exits the valve throughbranch port218. The cooled oil then flows back to the transmission throughoutlet conduit196.
• If the transmission oil returning to the transmission drops below the predetermined temperature, thecontrol unit258 de-energizes the solenoid, thereby causing thereturn spring244 to lift the valve member out of engagement with thevalve seat220. The oil is then permitted to bypass theheat exchanger172 as described above.
• In the reverse flow configuration,conduit196 becomes the inlet conduit receiving hot oil from the transmission, andconduit194 becomes the outlet conduit returning the cooled transmission oil to the transmission. In the reverse configuration, the flow through thevalve174 is the opposite of that described above, whether the transmission oil is above or below the predetermined temperature.
• It will be appreciated that any pressure peaks that might occur upon the closing ofvalve member222 are attenuated or modulated, becausevalve member222 can lift offvalve seat220 by such a pressure surge, sincevalve member222 is urged into position bycoil spring238 and is not solidly in engagement with thevalve seat220. In other words, thecoil spring238 can absorb pressure spikes in theinlet conduits196,188 so that they do not travel back and adversely affect the transmission.
• Another advantage ofbypass valve174 is that thetemperature sensor252 is located such that it is in continuous contact with oil flowing through thevalve174. Thus, the temperature sensor can respond quickly to changes in the oil temperature.
• Referring next toFIGS. 13,16 and17, three-port bypass valve204 will now be described in detail.Bypass valve204 is similar to bypassvalve174 includes a number of components which are either similar or identical to components of the four-port bypass valve174 described above. Similar reference numerals are used to describe similar elements ofvalve204 and detailed description of these elements is omitted.
• The principal difference betweenvalve204 andvalve174 is thatvalve204 has a valve housing294 provided with asingle branch port296 rather than a pair ofbranch ports216,218 as invalve174. The valve housing294 is otherwise the same as thevalve housing206 ofvalve174. Thesingle branch port296 is connected toconduits188 and196 through theconduit205. The operation ofvalve204 is substantially the same as described above with reference tovalve174, except that the transmission oil enters or exits thevalve204 through thesingle branch port296, depending on whether the oil flow is in the normal or reverse direction.
• In each of the valves illustrated inFIGS. 10 to 17, the electrical control unit is attached to the valve shaft so that the control unit and the valve shafts move together during operation of the valve.FIG. 18 illustrates four-port bypass valve298, similar tovalve174 shown inFIG. 14, having anelectrical control unit300 which is spaced from the valve shaft and is housed in thecontrol unit compartment260 which is separated from the remainder of thevalve298 by anannular flange302 extending inwardly from the side wall of thecap262. In this embodiment there is no spring inside thecap262. The remaining elements ofvalve298 are identical to the elements ofvalve174 and are identified by like reference numerals. Also, the operation ofvalve298 is substantially identical to the operation ofvalve174. Therefore, a detailed description of the elements ofvalve298, and their operation, are unnecessary.
• As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. The foregoing description is of the preferred embodiments and is by way of example only, and it is not to limit the scope of the invention.

Claims (18)

1. A bypass valve for a heat exchanger including a plurality of parallel tubular members having adjacent wall portions defining flow openings in communication to form flow manifolds, the bypass valve comprising:

a housing having a hollow plug portion with opposed plug walls defining inlet and outlet openings therein, the plug walls being adapted to be sealingly mounted between selected adjacent tubular member wall portions to allow fluid flow respectively between said flow manifolds and said inlet and outlet openings; the housing also having an actuator portion located adjacent to the plug portion;

an actuator releasably mounted in the actuator portion and comprising a reciprocating plunger extending into the plug portion and a solenoid having a central actuator shaft attached to the plunger, wherein the actuator shaft extends upon energization of the solenoid, so that the plunger blocks flow between the inlet and outlet openings, wherein the actuator shaft has a first end to which the plunger is attached, a second end, and a hollow interior, and wherein the actuator further comprises bias means for urging the actuator shaft to retract upon de-energization of the solenoid so as to unblock flow between said inlet and outlet openings; and

a temperature sensor for sensing a temperature of the fluid flowing through the heat exchanger, the temperature sensor being electrically coupled to the solenoid through one or more conductors, wherein the temperature sensor is located at the first end of the actuator shaft and the one or more conductors extend through the hollow interior of the actuator shaft to the second end thereof.

2. A bypass valve according toclaim 1, further comprising an electrical control unit mounted in the housing and electrically connected between the temperature sensor and the solenoid for controlling the movement of the plunger in accordance with the temperature sensed by the temperature sensor.

3. A bypass valve according toclaim 1, wherein the temperature sensor is a thermistor mounted on the plunger.

4. A bypass valve according toclaim 1, wherein the opposed plug walls of the housing plug portion are flat, parallel side walls defining said inlet and outlet openings.

5. A bypass valve according toclaim 4, wherein said side walls are spaced apart a predetermined distance so as to determine the spacing between adjacent heat exchanger tubular members.

6. A heat exchanger comprising:

a plurality of parallel, tubular members having adjacent wall portions defining flow openings in communication to form inlet and outlet manifolds for the flow of fluid through the tubular members; and

a bypass valve comprising

a housing having a hollow plug portion with opposed plug walls defining inlet and outlet openings therein, the plug walls being adapted to be sealingly mounted between selected adjacent tubular member wall portions to allow fluid flow respectively between said flow manifolds and said inlet and outlet openings; the housing also having an actuator portion located adjacent to the plug portion;

an actuator releasably mounted in the actuator portion and comprising a reciprocating plunger extending into the plug portion and a solenoid having a central actuator shaft attached to the plunger, wherein the actuator shaft extends upon energization of the solenoid, so that the plunger blocks flow between the inlet and outlet openings, wherein the actuator shaft has a first end to which the plunger is attached, a second end, and a hollow interior, and wherein the actuator further comprises bias means for urging the actuator shaft to retract upon de-energization of the solenoid so as to unblock flow between said inlet and outlet openings; and

a temperature sensor for sensing a temperature of the fluid flowing through the heat exchanger, the temperature sensor being electrically coupled to the solenoid through one or more conductors, wherein the temperature sensor is located at the first end of the actuator shaft and the one or more conductors extend through the hollow interior of the actuator shaft to the second end thereof.

7. A heat exchanger according toclaim 6, wherein the bypass valve further comprises an electrical control unit mounted in the housing and electrically connected between the temperature sensor and the solenoid for controlling the movement of the plunger in accordance with the temperature sensed by the temperature sensor.

8. A heat exchanger according toclaim 6, wherein the temperature sensor is a thermistor mounted on the plunger.

9. A heat exchanger according toclaim 6, wherein the tubular members are formed of plate pairs having enlarged distal end portions joined together to form said inlet and outlet manifolds, said plug walls being spaced-apart flat, parallel side walls defining said inlet and outlet openings and being joined to adjacent enlarged distal end portions of the adjacent plate pairs.

10. A heat exchanger according toclaim 6, wherein said side walls are spaced apart a predetermined distance so as to determine the spacing between adjacent heat exchanger tubular members.

11. A bypass valve for a heat exchanger, comprising:

(a) a housing comprising:

(i) a first opening and a second opening to permit fluid to flow through the valve;

(ii) a first valve chamber which is arranged between the first and second openings and is in flow communication with both the first and second openings;

(iii) a second valve chamber in flow communication with the first valve chamber;

(iv) a third opening in communication with the second valve chamber; and

(v) a valve port which is arranged between the first and second valve chambers, wherein the second valve chamber is arranged between the third opening and the valve port; and

(b) a temperature-responsive actuator mounted in the housing and comprising:

(i) a reciprocating sealing member extending into the first valve chamber;

(ii) a solenoid having a central actuator shaft attached to the sealing member, wherein the actuator shaft extends upon energization of the solenoid, so that the sealing member seals the valve port and blocks flow between the first and second valve chambers, wherein the actuator shaft has a first end to which the sealing member is attached, a second end, and a hollow interior;

(iii) bias means for urging the actuator shaft to retract upon de-energization of the solenoid so as to unblock flow between said inlet and outlet openings; and

(iv) a temperature sensor for sensing a temperature of the fluid flowing through the valve, the temperature sensor being electrically coupled to the solenoid through one or more conductors, wherein the temperature sensor is located at the first end of the actuator shaft and the one or more conductors extend through the hollow interior of the actuator shaft to the second end thereof.

12. A bypass valve according toclaim 11, further comprising an electrical control unit mounted in the housing and electrically connected between the temperature sensor and the solenoid for controlling the movement of the sealing member in accordance with the temperature sensed by the temperature sensor.

13. A bypass valve according toclaim 11, wherein the temperature sensor is a thermistor mounted on the first end of the actuator shaft.

14. The bypass valve according toclaim 11, wherein the actuator shaft and the first and second valve chambers are aligned along a common axis, and wherein the biasing means comprises a coil spring housed in the second valve chamber.

15. The bypass valve according toclaim 11, wherein the housing further comprises a fourth opening which is in flow communication with the second valve chamber, and wherein the second valve chamber is arranged between the third and fourth openings.

16. The bypass valve according toclaim 11, wherein the housing includes a valve cover which closes the first valve chamber and which has a central opening through which the actuator shaft extends, wherein the solenoid is mounted to the valve cover.

17. The bypass valve according toclaim 12, wherein the second end of the actuator shaft extends through the solenoid and is provided with a plunger plate to which the electrical control unit is mounted.

18. The bypass valve according toclaim 12, wherein the housing further comprises a control unit compartment in which electrical control unit is housed.

Images